The present invention relates to a low-cost television signal receiver and decoder, hereafter referred to as a “settop”, with built-in digital tuning, digital to analog conversion, and analog signal pass-through capabilities. The tuner within an analog television handles analog channel reception, including digital channels presented in analog form on a predetermined analog channel.
While television sets capable of receiving digital signals are becoming more popular, terrestrial television reception by most consumers' TVs is primarily handled in a composite analog format while cable customers often receive a mixture of digital and analog rebroadcast of terrestrial channels. Satellite customers often receive terrestrial channels over the air and digital programming from the satellite. Each analog television channel (whether transmitted “over the air” or on the cable) is transmitted on a 6 MHz channel using NTSC (National Television Standards Committee) format as provided in North America and Japan, or PAL (Phase Alternating Line) as provided in most of Europe. Terrestrial signal reception systems in common use include antennas and cable. With the exception of satellite dish and aerial antenna systems in large metropolitan areas, terrestrial antennas generally limit the number of program providers received by the consumer to a small number. The large channel carrying capacity of broadband cable is a successful alternative. The capacity of the broadband network allows many more channels to be broadcast to customers over copper coaxial cable and/or optical fibers. An analog settop box located at the customer facility tunes and descrambles incoming broadcasts. An example of such an analog settop box is the Impulses® 7000 manufactured by the Broadband Communications Sector of Motorola, Inc., Horsham, Pa., USA. These settop boxes tune to a desired analog frequency and modulate the signal onto an unused channel (usually channel 3 or 4) or provide baseband output. Modern analog televisions often have built in tuners capable of tuning all available analog cable frequencies. However, a settop box is still necessary to descramble scrambled analog broadcasts.
Cable operators have been deploying digital cable service to their customers to provide a wider array of programming and services. Digital cable service offers the advantage of expanded capacity on the transmission medium since up to six video programs can be multiplexed into a 6 MHz bandwidth formerly used for a single analog program. Digital cable can support increased picture quality, such as high definition (HDTV) and service offerings can be expanded as well to include Video on Demand (VOD), Pay Per View (PPV) and interactive shopping. Current generation television systems are beginning to offer digital input and decoding capabilities. However, to maintain backward compatibility with existing analog televisions, service providers offer settop terminals that can decode received digital data programs and output these programs in analog format. Examples include the Motorola Interactive Digital Settop Terminal (DCT-5000, 5100 and 5200) series of units. These units offer digital video, audio, and high speed-data services along with streaming media, PPV, Internet services, HDTV, and personal video recorder (PVR) capabilities. While these feature-rich units permit consumers to access myriad applications, they provide far more functionality than consumers may need for second or third TVs in the home, where simple video viewing of digital and analog programming is all that is required. In particular, the analog hardware in the settop adds substantial additional cost. As a result, there is a need to offer a low-cost settop unit, with simple decode capability, which would allow a consumer to receive digital or analog video program reception. The present invention provides a low-cost settop architecture that leverages existing television tuner hardware in the settop to solve the cost problem.